Apparatus and method for controlling coexistence interference within device in wireless communication system

ABSTRACT

The present invention provides an apparatus and a method for controlling coexistence interference within a device in a wireless communication system. The method discloses the following steps: performing triggering, in which a transmission, which is generated in a terminal, in a first frequency band of a first network system requests controlling of interference on a reception, which is generated in the terminal, in a second frequency band of a second network system; transmitting to a base station support information including information on a time section that can or cannot be used by the first network system of the second network system, due to the interference; and receiving from the base station reply information for accepting or denying interference control as a reply to the support information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/978,519, filed on Jul. 5, 2013, which is the National Stage Entry ofInternational Application PCT/KR2012/000144, filed on Jan. 6, 2012, andclaims priority from and the benefit of Korean Patent Application No.10-2011-0001971, filed on Jan. 7, 2011, which are incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION Field

The present invention relates to wireless communication and moreparticularly, an apparatus and a method for coordinating in-devicecoexistence interference based on time division multiplexing (TDM)scheme in a wireless communication system.

Background

A conventional wireless communication system exploits a single frequencyband for data transmission. For example, the second-generation wirelesscommunication system uses bandwidth of 200 KHz to 1.25 MHz while thethird-generation wireless communication system uses bandwidth of 5 MHzto 10 MHz. To meet the demand for ever-increasing transmission capacity,the recent 3GPP (3rd Generation Partnership Project) LTE (Long TermEvolution) or IEEE 802.16m is expanding the bandwidth up to 20 MHz ormore. Although it is essential to increase bandwidth to meet the demandfor high transmission capacity, supporting high bandwidth even whenquality of service required is low may incur large power consumption.

In this respect, multiple component carrier systems are now emerging,which define a carrier wave to use a predetermined frequency band andcenter frequency and support broadband data transmission and/orreception through a plurality of carrier waves. Both narrow andbroadband data communication are supported by utilizing one or morecarrier waves. For example, if a carrier wave corresponds to thebandwidth of 5 MHz, a maximum bandwidth of 20 MHz can be supported byusing four carrier waves.

Due to ubiquitous access networks today, users at different places areable to connect to networks different from each other and continuouslymaintain connectivity to the networks wherever they may be. In aconventional use case where a UE is allowed to communicate with only asingle network system, the user has to carry different types of devicessupporting the respective systems. As functions implemented in a singleUE are advanced and diversified these days, however, even a single UEcan perform communication with multiple network systems simultaneouslyand user's convenience is greatly enhanced.

However, in case a single UE performs communication simultaneouslythrough frequency bands of a plurality of network systems, in-devicecoexistence interference may occur. In-device coexistence interferencerefers to such kind of interference that causes interference caused bydata transmission in a particular frequency band on another frequencyband. For example, in case a single UE supports the Bluetooth and LTE(Long Term Evolution) system together, the in-device coexistenceinterference may be developed between the frequency bands of theBluetooth and the LTE system. The in-device coexistence interference isusually generated when separation between boundaries of frequency bandsin a heterogeneous network system is not wide enough.

Frequency division multiplexing (FDM) and time division multiplexing(TDM) may be used as the technique to avoid in-device coexistenceinterference. The FDM technique controls in-device coexistenceinterference developed between a first frequency band of a first networksystem and a second frequency band of a second network system byshifting the frequency band of either of the network systems. On theother hand, the TDM technique controls the in-device coexistenceinterference by separating transmission time of the first network systemfrom reception time of the second network system. However, there stillneeds an agreement about a specific operating procedure between a UE andan eNB for controlling in-device coexistence interference.

SUMMARY

An object of the present invention is to provide an apparatus and methodfor controlling in-device coexistence interference.

Another object of the present invention is to provide an apparatus andmethod for triggering transmission of assistance information accordingto in-device coexistence interference in a wireless communicationsystem.

A yet another object of the present invention is to provide an apparatusand method for transmitting information about in-device coexistenceinterference in a wireless communication system.

A still another object of the present invention is to provide anapparatus and method for controlling in-device coexistence interferencebased on TDM technique.

According to one aspect of the present invention, provided is a methodfor controlling interference due to a UE in a wireless communicationsystem. The method comprises performing triggering a request forcontrolling interference caused by transmission through a firstfrequency band of a first network system performed in a UE on receptionthrough a second frequency band of a second network system performed inthe UE; transmitting to an eNB assistance information includinginformation about a time interval unavailable or available for the firstor the second network system due to the interference; and receiving fromthe eNB response information accepting or rejecting control of theinterference in response to the assistance information.

According to another aspect of the present invention, provided is a UEcontrolling interference in a wireless communication system. The UEcomprises a triggering unit performing triggering a request forcontrolling interference caused by transmission through a firstfrequency band of a first network system performed in a UE on receptionthrough a second frequency band of a second network system performed inthe UE; an assistance information generating unit generating assistanceinformation including information about a time interval unavailable oravailable due to the interference; an assistance informationtransmitting unit transmitting the assistance information to an eNB; anda response information receiving unit receiving from the eNB responseinformation accepting or rejecting control of the interference inresponse to the assistance information.

According to yet another aspect of the present invention, provided is amethod for controlling interference due to an eNB in a wirelesscommunication system. The method comprises receiving from a UEassistance information requesting coordination of interference caused bytransmission through a first frequency band of a first network systemperformed in the UE on reception through a second frequency band of asecond network system performed in the UE; and transmitting to the UEresponse information accepting or rejecting control of the interferencein response to the assistance information.

The assistance information includes information about a time intervalunavailable or available for the first or the second network system dueto the interference.

According to still another aspect of the present invention, provided isan eNB controlling interference in a wireless communication system. TheeNB comprises an assistance information receiving unit receivingassistance information requesting coordination of interference caused bytransmission through a first frequency band of a first network systemperformed in a UE on reception through a second frequency band of asecond network system performed in the UE; a response informationgenerating unit generating response information accepting or rejectingcontrol of the interference in response to the assistance information; aresponse information transmitting unit transmitting the responseinformation to the UE; and an interference coordinator performingcontrol of the interference.

The assistance information includes information about a time intervalunavailable or available for the first or the second network system dueto the interference.

According to the present invention, the process of resolving coexistenceinterference within the device can be simplified and implementationthereof can be easily achieved and reverse compatibility with otherexisting processes can be maintained. Also, information about in-devicecoexistence interference exchanged between a UE and an eNB can beclearly defined and interference in the time domain can be effectivelyresolved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system to which embodimentsof the present invention are applied;

FIG. 2 illustrates in-device coexistence interference;

FIG. 3 is an example illustrating in-device coexistence interferenceacting on an LTE receiver from an ISM transmitter;

FIG. 4 illustrates a frequency band divided into the ISM band and theLTE band;

FIG. 5 illustrates one example where in-device coexistence interferenceis relieved by employing the FDM technique;

FIG. 6 illustrates another example where in-device coexistenceinterference is relieved by employing the FDM technique;

FIG. 7 illustrates one example where in-device coexistence interferenceis mitigated by employing the TDM technique;

FIG. 8 illustrates a transmit and receive timing in the time axis of theLTE and the ISM band employing the TDM technique;

FIG. 9 is a flow diagram illustrating a method for transmittinginformation about in-device coexistence interference according to oneembodiment of the present invention;

FIG. 10 illustrates assistance information according to one example ofthe present invention;

FIG. 11 illustrates assistance information according to another exampleof the present invention;

FIG. 12 illustrates assistance information according to a yet anotherexample of the present invention;

FIG. 13 is a flow diagram illustrating a method for controllinginterference performed by a UE according to one example of the presentinvention;

FIG. 14 is a flow diagram illustrating a method for controllinginterference performed by an eNB according to one example of the presentinvention;

FIG. 15 illustrates operation of a UE entering a DRX mode in caseresponse information according to one example of the present inventionis a DRX command message; and

FIG. 16 is a block diagram illustrating an apparatus controllingin-device coexistence interference according to one example of thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In what follows, part of the embodiments of the present document will bedescribed in detail with reference to exemplary drawings. In assigningreference symbols to constituting elements in each drawing, it should benoted that the same symbols are assigned to the same constitutingelements as possibly as can be even though they appear in differentdrawings. Also, in describing embodiments of the present invention, ifit is determined that detailed description of a related structure orfunction known for those in the art obscures the technical principles ofthe present invention, the corresponding description will be omitted.

Also, in describing constituting elements of the present document, termssuch as first, second, A, B, (a), (b), and the like can be used. Thoseterms are introduced only for the purpose of distinguishing aconstituting element from the others; therefore, inherentcharacteristics, order, or sequence of the corresponding constitutingelement is not limited by the terms. If a particular constitutingelement is described to be “linked to”, “combined with”, or “connectedto” a different constituting element, it should be understood that theconstituting element can be directly linked or connected to thedifferent constituting element but a third constituting element can alsobe “linked to”, “combined with”, or “connected to” the individualconstituting elements.

Also, the present document is related to a wireless communicationsystem; tasks performed in a wireless communication system can becarried out while a system controlling the corresponding wirelesscommunication system (for example, an eNB) controls the network ortransmits data or the tasks can be carried out in a UE combined with thecorresponding wireless network.

FIG. 1 illustrates a wireless communication system to which embodimentsof the present invention are applied.

With reference to FIG. 1, a wireless communication system is widelydeployed for providing various communication services such as voice,packet data, and so on; and comprises a user equipment (UE) 10, an eNB(evolved NodeB, eNodeB, eNB) 20, a wireless LAN access point (AP) 30,GPS (Global Positioning System) 40, and satellites. Here, wireless LANrefers to a device supporting the IEEE 802.11 technology, a wirelesscommunication standard, and the IEEE 802.11 can be used interchangeablywith the WiFi system.

The UE 10 can be located within a coverage formed by a plurality ofnetworks such as a cellular network, wireless LAN, broadcast network,satellite network, and so on. The latest UE 10 is equipped with aplurality of wireless transceivers to connect to various services andnetworks such as an eNB 20, wireless LAN access point 20, GPS 40, and soon at any place and time. For example, a smart phone is equipped with anLTE, WiFi, and Bluetooth transceiver and a GPS receiver. In thisrespect, design of UE 10 is getting more complicated to ensure goodperformance and at the same time, to incorporate much more transceiversinto the same UE 10. Therefore, this trend raises the possibility ofoccurrence of in-device coexistence interference even larger.

In what follows, downlink transmission refers to communication from theeNB 20 to the UE 10 while uplink transmission refers to communicationfrom the UE to the eNB 20. In the downlink transmission, a transmittermay be part of the eNB 20 while a receiver may be part of the UE 10.Similarly, in the uplink transmission, the transmitter may be part ofthe UE 10 while the receiver may be part of the eNB 20.

The UE 10 may be stationary or mobile and can be referred to bydifferent terms such as a mobile station (MS), user terminal (UT),subscriber station (SS), mobile terminal (MT), wireless device, and thelike. The eNB 20 refers to a fixed station communicating with the UE 10and can be referred to by different terms such as a base station (BS),base transceiver system (BTS), access point, Femto BS, relay, and thelike.

There is no limitation on the multiple access techniques used for awireless communication system. Various multiple access techniques suchas CDMA (Code Division Multiple Access), TDMA (Time Division MultipleAccess), FDMA (Frequency Division Multiple Access), OFDMA (OrthogonalFrequency Division Multiple Access), SC-FDMA (Single Carrier-FDMA),OFDM-FDMA, OFDM-TDMA, and OFDM-CDMA can be used. For uplink and downlinktransmission, a time division duplex (TDD) technique can be used, whichcarries out data transmission by using different time slots or afrequency division duplex (FDD) technique can be used, which carries outdata transmission by using different frequency bands.

Carrier aggregation (CA) supports a plurality of component carriers andis alternatively called spectrum aggregation or bandwidth aggregation.An individual carrier wave grouped together by carrier aggregation iscalled a component carrier (in what follows, it is called CC). Each CCis defined by its bandwidth and center frequency. Carrier aggregation isemployed to support growing throughput, prevent increase of costs due tobroadband RF (Radio Frequency) devices, and ensure compatibility withthe existing systems. For example, if five CCs are allocated withgranularity of 5 MHz bandwidth for each carrier, a maximum of 25 MHzbandwidth can be supported. In what follows, a multiple carrier systemrefers to the system supporting carrier aggregation. The wirelesscommunication system of FIG. 1 can be a multiple carrier system.

According to carrier aggregation, frequency band of a system cancomprise a plurality of carrier frequency. Here, carrier frequencyrefers to the center frequency of a cell. A cell denotes a downlink CCand an uplink CC. Similarly, a cell can denote a combination of adownlink CC and an optional uplink CC. Also, in the usual case wherecarrier aggregation is not considered, a single cell is constructedalways in the form of a pair of a downlink and uplink CC.

FIG. 2 illustrates in-device coexistence interference.

With reference to FIG. 2, the UE 10 comprises an LTE RF module 21, GPSRF module 22, and Bluetooth/WiFi RF module 23. A transmit and receiveantenna 24, 25, 26 is connected to each RF module. In other words,various types of RF modules are installed close to each other within asingle device platform. At this time, transmission power of one RFmodule can be much larger than the reception power level onto other RFreceivers. In this case, if frequency spacing between RF modules is notlarge enough and a sophisticated filtering technique is not available, atransmission signal from an arbitrary RF module can easily causesignificant interference on the receivers of other RF modules within thesame device. For example, (1) is an example where a transmission signalof the LTE RF module 21 causes in-device coexistence interference on theGPS RF module 22 and the Bluetooth/WiFi RF module 23; and (2) is anexample where a transmission signal of the Bluetooth/WiFi RF module 23causes in-device coexistence interference on the LTE RF module 21.

FIG. 3 is an example illustrating in-device coexistence interferenceacting on an LTE receiver from an ISM transmitter. ISM (Industrial,Scientific and Medical) band refers to the frequency bands that can beused freely without permission for industrial, scientific and medicalpurposes.

With reference to FIG. 3, the radio band of a signal received by the LTEreceiver overlaps the radio band of a transmission signal of the ISMtransmitter. In this case, in-device coexistence interference can bedeveloped.

FIG. 4 illustrates a frequency band divided into the ISM band and theLTE band.

With reference to FIG. 4, radio band 40, 7, and 38 belong to the LTEband. The radio band 40 occupies the frequency range from 2300 to 2400MHz in the TDD mode while the radio band 7 occupies the frequency rangefrom 2500 to 2570 MHz as an uplink in the FDD mode. And the radio band38 occupies the frequency range from 2570 to 2620 MHz in the TDD mode.Meanwhile, the ISM band is used for a WiFi channel and a Bluetoothchannel and occupies the frequency range from 2400 to 2483.5 MHz. Here,in-device coexistence interference situations are summarized in theTable 1.

TABLE 1 Interference band Type of interference Band 40 ISM Tx 

 LTE TDD DL Rx Band 40 LTE TDD UL Tx 

 ISM Rx Band 7 LTE FDD UL Tx 

 ISM Rx Band 7/13/14 LTE FDD UL Tx 

 GPS Rx

With reference to Table 1, the notation of ‘a→b’ representing type ofinterference indicates a situation where transmission of a causesin-device coexistence interference on reception of b. Therefore, in theradio band 40, transmission in the ISM band causes in-device coexistenceinterference on the TDD downlink reception (LTE TDD DL Rx) of the LTEband. Although a filtering scheme may somewhat alleviate the in-devicecoexistence interference, it is not sufficient. If FDM or TDM techniqueis applied in addition to the filtering scheme, in-device coexistenceinterference can be alleviated more efficiently.

FIG. 5 illustrates one example where in-device coexistence interferenceis relieved by employing the FDM technique.

With reference to FIG. 5, the LTE band can be shifted to avoidoverlapping with the ISM band. And as a result, this introduces ahandover of the UE from the ISM band. However, to this end, there needsa method for legacy measurement or new signaling to accuratelytriggering a mobility procedure or radio link failure (RLF) procedure.

FIG. 6 illustrates another example where in-device coexistenceinterference is relieved by employing the FDM technique.

With reference to FIG. 6, the ISM band can be reduced and moved awayfrom the LTE band. However, this technique can cause a backwardcompatibility problem. In the case of Bluetooth, the backwardcompatibility problem can be somewhat relieved due to an adaptivefrequency hopping mechanism but it may not be the case for WiFi.

FIG. 7 illustrates one example where in-device coexistence interferenceis mitigated by employing the TDM technique.

With reference to FIG. 7, if reception timing in the LTE band is madenot to overlap with transmission timing in the ISM band, in-devicecoexistence interference can be avoided. For example, if a signalbelonging to the ISM band is transmitted at time t₀, a signal belongingin the LTE band is made to be received at time t₁.

In this way, a transmit and receive timing employing the TDM techniquealong the time axis for a signal in the LTE and ISM band can berepresented as shown in FIG. 8. By adopting the scheme as describedabove, in-device coexistence interference can be avoided withoutincorporating band-to-band movement of the LTE and ISM band. The radiointerval of FIG. 8 where signal transmission is not carried out for eachband is called a blank transmission interval.

As described above, each of the TDM and FDM technique has its owncharacteristics. The TDM technique can also be applied for such asituation where only one carrier band is allocated for the UE; however,since temporal resources are shared among network systems, interferencemay become too severe or communication may be almost impossibledepending on the type of traffic utilized for the UE. Although the FDMtechnique cannot be applied for such a case where only one carrier bandis set up for the UE, since the technique is capable of completelyavoiding a band affected by interference, occurrence of interference isless sensitive to the type of traffic than for the TDM technique. If theTDM and FDM technique are combined together to carefully complementdisadvantages of the two techniques, interference can be controlled moreefficiently.

FIG. 9 is a flow diagram illustrating a method for transmittinginformation about in-device coexistence interference according to oneembodiment of the present invention.

With reference to FIG. 9, the UE triggers a request for controllinginterference based on the TDM technique S900. As described below, therecan be three different cases where a request for controllinginterference based on the TDM technique is triggered. It should be notedthat the following three cases are just examples and thus, the technicalprinciples of the present invention are not limited to the examplesshown below.

(1) Detection of in-device coexistence interference: this applies forthe case where the UE carries out transmission through a first networksystem and reception through a second network system and the UE detectsinterference acting on the reception by the transmission. For example,this corresponds to a case where the UE detects interference caused bytransmission based on Bluetooth or WiFi on the reception in the LTEsystem. In the case of FIG. 2, the UE detects whether a transmissionsignal from Bluetooth or WiFi RF module 23 causes interference on areception signal of the LTE RF module 21. As one example, the UE candetect in-device coexistence interference by using asignal-to-interference noise ratio (SINR).

As another example, the UE can detect in-device coexistence interferenceby using RSRP (Reference Signal Received Power) or RSRQ (ReferenceSignal Received Quality). For example, suppose that the UE transmits asignal y through a different RF module such as a WiFi module whilereceiving a signal x from a eNB through the LTE RF module. At this time,when the SINR of the signal y is large enough to exceed a predeterminedthreshold value and acts as interference on the signal x, the UE candetect occurrence of in-device coexistence interference.

(2) Rejection of interference coordination based on FDM technique: thisapplies for the case where interference coordination based on the FDMtechnique is not allowed though the UE requests from the eNBinterference coordination based on the FDM technique. As one example,this may correspond to a case where the UE receives from the eNBresponse information indicating that interference coordination based onthe FDM technique cannot be carried out. Similarly, it may be the casewhere the UE requests interference coordination based on the FDMtechnique but a response to the request is not received for apredetermined time period. Or it may correspond to a case where the UErequest interference coordination based on the FDM technique but itreceives response information commanding carrying out interferencecoordination based on the TDM technique other than the FDM technique.The above scenario is intended to recommend that the UE should carry outinterference coordination based on the TDM technique as an alternativesolution since interference coordination is now impossible because ofthe eNB's decision. At this time, the response information may includespecific TDM pattern information or an indicator indicating triggeringinterference coordination based on the TDM technique.

(3) Failure of interference coordination: this applies for the casewhere interference problem is not resolved up to an expectation leveleven though interference coordination based on the TDM technique iscarried out. Here, an element that determines the expectation level maybe a result of channel measurement or an error rate of packettransmission. In other words, degree of interference can be evaluated bythe result of channel measurement or error rate of packet transmission.The error rate of packet transmission refers to an error rate of packetsreceived from a device communication with the UE or the 3GPP LTE (3rdPartnership Project Long Term Evolution) eNB. One example of a methodfor measuring the error rate can be inspection of CRC (Cyclic RedundancyCheck) error of HARQ (Hybrid Automatic Repeat request) packets.

At this time, a request for interference coordination is re-triggeredfor re-attempting interference coordination based on the TDM technique.

Again in the step of S900, if a request for interference coordination istriggered, the UE transmits to the eNB assistance information requiredfor carrying out interference coordination S905. Assistance informationcan be defined in various ways depending on a view point. For theconvenience of description, suppose that transmission Tx through a firstnetwork system performed by the UE causes interference on the receptionRx through a second network system performed by the UE in theinterference interval T₁ to T₂ for each period and does not causeinterference in the non-interference interval T₂ to T₃. Since the firstnetwork generates interference, it can be called an aggressor systemwhile the second system can be called a victim system since it receivesinterference.

If the eNB is aware of the interference interval T₁ to T₂ or thenon-interference interval T₂ to T₃, the eNB can control interferencebased on the TDM technique by taking into account the intervals.

As one example, the eNB can set up scheduling for the Tx to be performedin the non-interference interval T₂ to T₃ other than the interferenceinterval T₁ to T₂. On the other hand, since the Rx is continuouslyperformed in the predetermined interference interval T₁ to T₂, thescheduling above puts higher priority in the victim system than theaggressor system. At this time, the eNB may correspond to an eNBbelonging to the aggressor system.

As an opposite example, the eNB can set up scheduling for the Rx to beperformed in the non-interference interval T₂ to T₃ other than theinterference interval T₁ to T₂. On the other hand, since the Rx iscontinuously performed in the predetermined interference interval T₁ toT₂, the scheduling in this case puts higher priority in the aggressorsystem than the victim system.

As described above, performing interference coordination based on theTDM technique by prioritizing a particular system may be agreed uponbeforehand between the UE and the eNB or determined by the eNB accordingto its own scheduling. For example, suppose the aggressor system is aWiFi system and important information such as system information istransmitted through the interference interval T₁ to T₂. Since systeminformation has a relatively high priority, if the WiFi system causesinterference on other systems in the interval T₁ to T₂, the eNB controlssuch that transmission and reception of other systems is not carried outin the interference interval T₁ to T₂.

As described above, from the standpoint of a system with a low priority,the interference interval can be defined as unusable whereas thenon-interference interval can be defined as usable. If the UE informsthe eNB of the interference interval (or unusable interval) or thenon-interference interval (or usable interval), the eNB can performinterference coordination by referring to the information.

The assistance information can be the information indicating theinterference interval (or unusable interval) or the informationindicating the non-interference interval (or usable interval). Aspecific form of the assistance information and a method for indicatingthe interference or non-interference interval will be described later.

Again, in the step of S905, the eNB receiving the assistance informationcarries out interference coordination based on the TDM technique S910.Here, interference coordination can be defined as a kind of schedulingthat controls timing at which transmission or reception of the UE iscarried out.

As one example, the eNB can carry out scheduling based on theinterference and non-interference interval. For example, the eNB can setup scheduling such that the UE does not carry out transmission orreception in the interference interval. Or the eNB can set up schedulingsuch that the UE carries out transmission or reception in thenon-interference interval.

As another example, the eNB can carry out a discontinuous reception(DRX) procedure. The DRX procedure can be a DRX command or DRXreconfiguration message, which will be described later.

The eNB transmits to the UE response information accepting or rejectinga request for interference coordination S915. If the eNB determines fromthe step of S910 that interference coordination based on the TDMtechnique cannot be carried out, the eNB transmits to the UE responseinformation accepting a request for interference coordination. Theresponse information accepting a request for interference coordinationcan be varied according to an embodiment of interference coordinationbased on the TDM technique described in the step of S910. As oneexample, the response information accepting a request for interferencecoordination can be a DRX reconfiguration message. As another example,the response information accepting a request for interferencecoordination can be a DRX command message. As a yet another example, theresponse information accepting a request for interference coordinationcan be a simple ACK (acknowledgement).

On the other hand, if the eNB rejects a request for interferencecoordination, the eNB can transmit NACK (Non-acknowledgement) asresponse information rejecting a request for interference coordinationor the eNB may not respond at all, never transmitting the responseinformation to the UE.

In what follows, the assistance information will be described in moredetail. The assistance information can be a message generated in the RRC(Radio Resource Control) layer or MAC (Medium Access Control) layer orcan correspond to physical layer signaling.

(1) The assistance information can indicate the interference ornon-interference interval for a predetermined time period in the form ofbitmap.

FIG. 10 illustrates assistance information according to one example ofthe present invention.

With reference to FIG. 10, the structure of an LTE frame comprises aplurality of subframes, each of which lasts 1 ms. If it is assumed thatan interference interval is defined by units of subframes, each bitconstituting the bitmap corresponds to one subframe. For example, if thebitmap is ‘1’, it indicates that the corresponding subframe is aninterference interval while if the bitmap is ‘0’, it indicates that thecorresponding subframe is a non-interference interval. Of course, whatis indicated by the bitmap ‘1’ and ‘0’ can be defined in the oppositeway as described above. Although FIG. 10 assumes that the interferenceinterval is defined by the units of subframes, the above assumption isonly an example and n subframes can be grouped together to correspond toa single bit as a single interference interval. The interferenceinterval doesn't have to be represented by the units of subframes butcan be defined by the units of arbitrary time intervals such as 1.5 ms,0.8 ms, and so on. Furthermore, in terms of usable or unusable intervalfor the LTE system, the bitmap ‘1’ can be defined to specify the usableinterval while the bitmap ‘0’ can be defined to specify the unusableinterval.

Meanwhile, a bitmap indicating an interference interval/non-interferenceinterval of an uplink and a bitmap indicating an interferenceinterval/non-interference interval of a downlink can be distinguishedfrom each other and the interference interval/non-interference intervalcan be indicated by a single bitmap irrespective of the uplink anddownlink.

(2) Assistance information can indicate a time interval that cannot bescheduled (or scheduled).

FIG. 11 illustrates assistance information according to another exampleof the present invention.

With reference to FIG. 11, a scheduled interval and a unscheduledinterval is repeated for each arbitrary period P for the UE. Here, thescheduled interval refers to an interval for which the UE can bescheduled in a particular network system while the unscheduled intervalrefers to an interval for which the UE cannot be scheduled in theparticular network system.

Therefore, the UE can transmit to the eNB information about either ofthe scheduled interval or unscheduled interval; or information aboutboth the intervals as assistance information.

(3) Assistance information can indicate a scheduled interval or aunscheduled interval within a DRX period.

FIG. 12 illustrates assistance information according to a yet anotherexample of the present invention.

With reference to FIG. 12, the UE can operate in a DRX mode where asignal is not received for predetermined time duration according to apredetermined DRX period. Parameters determining the DRX mode include aDRX cycle, on-duration time, and an inactivity timer. The DRX cycle is aperiod at which the UE is woken up from the DRX mode and the on-durationtime corresponds to the duration for which the UE is kept in theon-state periodically.

The UE can determine whether a PDCCH scheduled for the UE exists duringthe on-duration time. If the UE is scheduled for the on-duration time,the UE is kept in the on-state until the scheduling is completed. Thetime instant at which the scheduling is completed will be the timeinstant at which the inactivity timer is terminated from the timeinstant of the last PDCCH scheduling. On the other hand, if PDCCHscheduling does not exist for the on-duration time, the UE re-entersinactivity of the DRX mode after the on-duration time is passed.

At this time, if transmission or reception timing of the UE in the DRXmode is to be changed by interference coordination based on the TDMtechnique, the change has to be carried out at least within a range thatdoes not influence operation of the DRX cycle. For example, in casetransmission or reception of the UE is constrained to be performed forthe on-duration time and not for the inactivity duration, the UE needsto inform the eNB of the on-duration time or inactivity duration of theUE. This is intended for the eNB not to allow the UE to be scheduled forthe inactivity duration at the time of interference coordination.

As one example, assistance information includes information about theon-duration time or inactivity time itself. As another example, theassistance information includes information about the ratio of theinactivity time to the DRX cycle. For example, if the DRX cycle is 4 msand the inactivity time is 3 ms, the ratio of the inactivity time to theDRX cycle is ¾ and the ratio information is included in the assistanceinformation.

(4) Assistance information can include information about increase ofunscheduled interval. The assistance information can deliver the amountof increase or decrease from the information about increase ofunscheduled interval. The amount of increase or decrease can berepresented in the form of multiples or additions. In case theassistance information represents the increase or decrease of theunscheduled interval in the form of multiples, the assistanceinformation is represented in the form of N or 1/N. For example, suppose¼ of the entire DRX cycle is a unscheduled interval. If the amount ofincrease in the form of multiples is 2, the unscheduled interval is ½.If the amount of increase in the form of multiples is ½, the unscheduledinterval is ⅛. The case where the information about increase ofunscheduled interval is represented in the form of additions correspondsto addition or subtraction applied to the assistance information. Forexample, if the amount of increase is ¼, the unscheduled interval is ½(namely, ¼+¼=½) while if it is −⅛, the unscheduled interval is ⅛(namely, ¼−⅛=⅛).

(5) Assistance information can include ACK indicator.

In case the eNB recommends interference coordination based on the TDMtechnique even though the UE requests interference coordination based onthe FDM technique, the UE triggers a request for interferencecoordination based on the TDM technique and transmits assistanceinformation included the ACK indicator to the eNB.

FIG. 13 is a flow diagram illustrating a method for controllinginterference performed by a UE according to one example of the presentinvention.

With reference to FIG. 13, the UE triggers a request for interferencecoordination based on the TDM technique S1300. Triggering of a requestfor interference coordination is carried out due to i) detection ofin-device coexistence interference, ii) rejection of interferencecoordination based on the FDM technique, and iii) failure ofinterference coordination based on the TDM technique as described inFIG. 9.

The UE transmits assistance information to the eNB S1305. The assistanceinformation is such kind of information that informs of an interferenceinterval in which in-device coexistence interference is generated or anon-interference interval directly or indirectly. As one example, theassistance information can indicate the interference or non-interferenceinterval in a predetermined time period in the form of bitmap. Asanother example, the assistance information can indicate an unscheduledtime interval (or scheduled time interval). As a yet another example,the assistance information can indicate a scheduled interval orunscheduled interval in the DRX cycle. As a still another example, theassistance information can include information about increase ofunscheduled interval. As a further example, the assistance informationcan include the ACK indicator.

The UE determines whether interference coordination based on the TDMtechnique is carried out S1310. As one example, if response informationindicating acceptance of interference coordination is received from theeNB in response to the assistance information transmitted by the UE, theUE can determine that a process of interference coordination is supposedto be carried out.

If it is determined that a request for interference coordination isaccepted, the UE operates according to interference coordination basedon the TDM technique S1315.

If it is determined that a request for interference coordination isrejected, the UE either triggers again the request for interferencecoordination based on the TDM technique or requests interferencecoordination based on the FDM technique S1320.

FIG. 14 is a flow diagram illustrating a method for controllinginterference performed by an eNB according to one example of the presentinvention.

With reference to FIG. 14, the eNB receives assistance information fromthe eNB S1400. The assistance information provides information requiredfor controlling in-device coexistence interference based on the TDMtechnique. The eNB can know the interference in which in-devicecoexistence interference is generated or non-interference interval fromthe assistance information.

In response to the reception of the assistance information, the eNBtransmits to the UE response information accepting or rejecting arequest for interference coordination S1405. If the eNB determines thatinterference coordination based on the TDM technique cannot be carriedout, the eNB transmits to the UE response information rejecting arequest for interference coordination. On the other hand, if the eNBdetermines that interference coordination based on the TDM technique canbe carried out, the eNB transmits to the UE response informationaccepting the request for interference coordination.

The response information can be implemented either by a MAC message orphysical layer signaling. As one example, response information acceptinga request for interference coordination can correspond to the DRXreconfiguration message. As another example, the response informationaccepting a request for interference coordination can be a simple ACK.As a yet another example, the response information rejecting a requestfor interference coordination can be NACK. As a still another example,to reject a request for interference coordination, the eNB can operatein such a way that it does not respond at all, never transmitting theresponse information.

The eNB carries out interference coordination based on the TDM techniqueS1410. As one example of interference coordination, the eNB can performscheduling based on an interference interval and non-interferenceinterval. For example, the eNB can set up scheduling such thattransmission or reception of the UE is not carried out in theinterference interval while the UE is scheduled in the non-interferenceinterval.

As another example of interference coordination, the eNB carries out adiscontinuous reception (DRX) procedure. This applies for the case wherethe UE operates in the DRX mode and assistance information received fromthe UE indicates a scheduled interval or unscheduled interval in the DRXcycle. The DRX procedure can be a DRX command or DRX reconfigurationmessage. In particular, in case interference coordination is carried outfrom the DRX command, the UE can operate as shown in FIG. 15.

With reference to FIG. 15, if a PDCCH scheduling is applied within theDRX cycle, the UE holds the on-duration time. Afterwards, if the DRXcommand is given, the UE enters the inactivity time. Meanwhile, in caseinterference coordination is carried out as the DRX reconfigurationprocedure, the eNB can control interference by changing DRXconfiguration parameters.

FIG. 16 is a block diagram illustrating an apparatus controllingin-device coexistence interference according to one example of thepresent invention.

With reference to FIG. 16, the UE 1600 and the eNB 1650 exchangesinformation about in-device coexistence interference. Information aboutin-device coexistence interference includes assistance informationtransmitted by the UE 1600 and response information transmitted by theeNB 1650.

The UE 1600 includes an interference coordination request triggeringunit 1605, assistance information generating unit 1610, assistanceinformation transmitting unit 1615, and response information receivingunit 1620.

The interference coordination request triggering unit 1605 triggers arequest for interference coordination from the eNB 1650 in casein-device coexistence interference is generated. The in-devicecoexistence interference can be generated in the following cases.

For example, suppose the UE, while receiving a signal x from the eNB1650 through the LTE RF module, transmits a signal y through another RFmodule such as WiFi module. At this time, if the ratio of receivedsignal to interference noise of the signal y exceeds a predeterminedthreshold value and acts on the signal x as interference, in-devicecoexistence interference is generated. Here, Although SINR has been usedas a reference of interference occurrence, the reference is not limitedto the above example but RSRP (Reference Signal Received Power) or RSRQ(Reference Signal Received Quality) can be used as a reference.

The interference coordination request triggering unit 1605 triggers arequest for interference coordination if i) in-device coexistenceinterference is detected; ii) interference coordination based on the FDMtechnique is rejected; or iii) interference coordination based on theTDM technique fails as described in FIG. 9.

The assistance information generating unit 1610 generates assistanceinformation if a request for interference coordination is triggered. Theassistance information is such kind of information that informs aninterference interval in which in-device coexistence interference isgenerated or non-interference interval directly or indirectly. As oneexample, the assistance information can indicate the interference ornon-interference interval in a predetermined time period in the form ofbitmap. As another example, the assistance information indicates aunscheduled time interval (or scheduled time interval). As a yet anotherexample, the assistance information indicates a scheduled interval orunscheduled interval within the DRX period. As a still another example,the assistance information includes information about increase ofunscheduled interval. As a further example, the assistance informationincludes ACK indicator.

The assistance information transmitting unit 1615 transmits assistanceinformation to the eNB 1650. At this time, the assistance informationtransmitting unit 1615 can transmit the assistance information throughan RRC message, MAC message, or physical layer signaling.

The eNB 1650 includes an assistance information receiving unit 1655,interference coordination performing unit 1660, response informationgenerating unit 1665, and response information transmitting unit 1670.

The assistance information receiving unit 1655 receives assistanceinformation from the UE 1600.

The assistance coordination performing unit 1660 determines whether tocontrol in-device coexistence interference generated in the UE andcarries out interference coordination. As one example, the interferencecoordination performing unit 1660 can carry out scheduling based on aninterference interval and non-interference interval. As one example, theinterference coordination performing unit 1660 can set up schedulingsuch that transmission or reception of the UE is not carried out in theinterference interval while the UE is scheduled in the non-interferenceinterval. As another example, the interference coordination performingunit 1660 carries out interference coordination through a DRX procedure.This applies for the case where the UE 1600 operates in the DRX mode andassistance information received from the UE 1600 indicates a scheduledinterval or unscheduled interval within the DRX period. Thediscontinuous reception procedure may correspond to a DRX command or DRXreconfiguration message.

The response information generating unit 1665 generates responseinformation accepting or rejecting interference coordination accordingto the decision of the interference coordination performing unit 1660.As one example, response information accepting a request forinterference coordination can correspond to the DRX reconfigurationmessage. As another example, the response information accepting arequest for interference coordination can be a simple ACK. As a yetanother example, the response information rejecting a request forinterference coordination can be NACK. As a still another example, toreject a request for interference coordination, the eNB can operate insuch a way that it does not respond at all, never transmitting theresponse information.

The response information transmitting unit 1670 transmits responseinformation to the UE 1600. At this time, the response informationtransmitting unit 1670 can transmit the response information through anRRC message, MAC message, or physical layer signaling.

Embodiments above are provided to illustrate the technical principles ofthe present invention; thus, it should be understood that those skilledin the art to which the present invention belongs will be able to changeor modify the embodiments in various other ways unless changes ormodifications of the embodiments depart from the inherentcharacteristics of the present invention. Therefore, those embodimentsdisclosed in this document are not intended to limit the technicalprinciples of the present invention but to describe the technicalprinciples; and the technical scope of the present invention is notlimited by those embodiments. The technical scope of the presentinvention should be interpreted by the appended claims and all thetechnical principles belonging to the scope equivalent to that definedby the claims should be understood to be included in the claimed scopeof the present invention.

1. A method for coordinating in device coexistence (IDC) interference bya user equipment, the method comprising: transmitting, to an eNodeB(eNB), first assistance information for a first coordination of IDCinterference through a first frequency, the first assistance informationcomprising information of the first frequency of a Long Term Evolution(LTE) frequency band; transmitting, to the eNB, second assistanceinformation for a second coordination of IDC interference, the secondcoordination being based on a Time Division Multiplexing (TDM) techniquewhen a change of the first assistance information occurs; and receiving,from the eNB, a response responsive to the second assistanceinformation, wherein the response comprises information indicatingwhether the second assistance information is accepted or rejected. 2-15.(canceled)